Encounter some chemistry problems on Barron's study guide.

[Smooth Operater]

---

Members do not see this ad.

Hey guys. I just finished practicing one of sample exams on the Barron's study book.

I encountered few chemistry questions that I don't know how to solve after looking at the answer. If anyone is willing to help me out, can you give me some tips or explanation on how to solve the questions that I am stucked on. 🙂 I think it is a good practice for you guys too. 😀 Thank you so much for taking the time !!! 🙂


Q: the diffusion rate of methane gas compared to that of helium is?
A: the answer is "half of fast". Why is it so?

Q: How many atoms of carbon are in 4.00E-8 grams of C3H8?
A: 4.00E4
I kept getting 1.64E15 which is the wrong answer.

Q: An alloy contains atoms of
A: one element and has the properties of a metal
I thought alloy is a homogeneous mixture or solid solution of two or more metals, hence has more than one elements?

Q: if all of the chloride in a 5.0 gram sample of an unknown metal chloride is precipitated as AgCl with 70.0 milliliters of 0.201 M AgNO3, what is the precentage of chloride in the sample?
A: answer is none of above given all the choices.
But, how would you carry about the calculation to solve this problem?

 

[mikester2]

Have you tried looking it up in your text book? I find this more helpful in terms of learning then having someone tell you the answer. I will just help you with the first one, because i am lazy =\.

Rate of diffusion methane compared to helium is equal to square root of the molecular weight of helium devided by methane. Note that this is inverse. So don't be tempted to devide methane by helium.

Molecular weight of methane is 16
Molecular weight of helium is 4.
4/16 is 1/4
take the square root of that which is 1/2. Therefore the rate is half.

Hey guys. I just finished practicing one of sample exams on the Barron's study book.

I encountered few chemistry questions that I don't know how to solve after looking at the answer. If anyone is willing to help me out, can you give me some tips or explanation on how to solve the questions that I am stucked on. 🙂 I think it is a good practice for you guys too. 😀 Thank you so much for taking the time !!! 🙂


Q: the diffusion rate of methane gas compared to that of helium is?
A: the answer is "half of fast". Why is it so?

Q: How many atoms of carbon are in 4.00E-8 grams of C3H8?
A: 4.00E4
I kept getting 1.64E15 which is the wrong answer.

Q: An alloy contains atoms of
A: one element and has the properties of a metal
I thought alloy is a homogeneous mixture or solid solution of two or more metals, hence has more than one elements?

Q: if all of the chloride in a 5.0 gram sample of an unknown metal chloride is precipitated as AgCl with 70.0 milliliters of 0.201 M AgNO3, what is the precentage of chloride in the sample?
A: answer is none of above given all the choices.
But, how would you carry about the calculation to solve this problem?

 

[HITMAN]

Edited.

 

[Smooth Operater]

THANKS mikester2! I tried to look for the solution for finding the diffusion rate of methane gas compared to that of helium by using my textbook and review notes. I just don't recall or know which topic is this questions related to. Maybe somone can give me some hints. I just don't understand why do we squared root the molecular weight of the helium. Thanks. !